We have synthesized an amphiphilic rigid-flexible macrocycle (fcoil = 0.68) consisting of hexa-p-phenylene and aliphatic polyether chain. The macrocyclic molecule in bulk state self-organizes into a 2-D body-centered rectangular structure (a = 4.3 nm and b = 6.3 nm). In aqueous solution, the macrocycle self-assembles into well-defined ribbonlike aggregates with a rod tilt relative to the ribbon normal at the initial stage. These elementary fibrils are further coiled to form a tubular structure consisting of coiled ribbons with a uniform diameter of about 20 nm and a regular pitch of 4.7 nm, as confirmed by TEM experiments. The internal diameter and the wall thickness of the nanotube are measured to be 14 and 3 nm, respectively.